Mechanical refrigerating system



1944- R. w. wA'rERFlLL MECHANICAL REFRIGERATING SYSTEM Filed Aug. 3/1940 4 Sheets-Sheet 1 INVENTOR W MMM 2M, 21 w ATTORNEYS.

Feb. 8, 1944. R. w. WATERFILL MECHANICAL BEFRIGERATING SYSTEM Filed Aug.5, '1940' 4 Sheets-Sheet 2 INVENTOR ATTORNEYS.

Feb. 8, 1944.

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4 Sheets-Sheet 4 @N O MW O JO O O O R. W. WATERFILL Filed Aug. 3, 1940ATTOR N EYS o0 aooqoo o o m OO 30m 0 0 0 000 om OOOOOAYQO OO 000; o o 00 0 o ooo O o w MECHANICAL REFRIGERATING SYSTEM Feb; 8, 1944.

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Patented Feb. 8, 1944 rQM EDh T PATENT E,

v I 2,341,132 MECHANICAL nnrmemmrme SYSTEM Robert W. Waterfill,Montclair, N.- J., assignor to Buensod-Stacey, Incorporated, acorporation of Delaware Application August a, 1940, Serial No. 350,785

13 Claims.

This invention relates to improvements in mechanical refrigeratingequipment.

The principal object of the invention is to simpllfythe construction andoperation of mechanical refrigerating systems, particularly those of thelow-pressure class, to render such systems more compact and of lesserweight as compared with prior structures of equal refrigeratingcapacity, to arrange the components of such systems in a way which willfacilitate manufacture as well as servicing of the equipment after ithas been installed, to. minimize the quantity compression, and a drivingmotor, which is adapted to be housed in one end of a casing whichalsoserves as the shell of the evaporator end of a casing which serves asthe shell .of a

shell-and-tube evaporator. for the system, and the other in a casingwhich serves as a part of the condenser of the system.

Yet anotherobject of the invention is to do away with troublesome andexpensive pumping units and other accessories such as are commonlyemployed at the present time in lowpressure refrigerating systems forwithdrawing [liquid refrigerant from the base of the shell and forshowering it over the tube bank of the evap- "A further object of theinvention is to pro- [vide a shell-and-tube evaporator of the nonfioodedtype, that is to say,one wherein the tube It is a still more specificobject of the lnven tion .to. provide an evaporatorof' the foregoincharacter with means which serve to confine vapor generated in the lowerpart of the tube bank in such a way as to cause that vapor to assist inthe general circulation of t refrigerant throughout the tube bank. v

The foregoing and otherobjects, as well as various features of theinvention, will be more fully understood from a. consideration of the,

following description whenread in the light of the accompanyingdrawings, in which- Figure l is an elevational view of the completemechanical refrigerating system of the-present 5 invention, certainparts thereof being broken away better to show' underlying ones;

Fig. 2 is an elevational view, partly illzSGCtiO and on an enlargedscale, of the compressorevaporator unit of Fig. 1, and particularlyillus-z trating the construction of the evaporator;

, Fig. 3 is a sectional view, on an enlarged scale, of a fragment of thefirst stage of the first compressor unit of Fig. l; v

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 2, and on anenlarged scale, to-show certain details of the evaporator construction;

Fig. 5 is a plan view, again on an enlargedevaporator of Fig.2; and

Fig. 6 is a cross-sectional view of a modified scale, of a fragmentof'the, tube bank: of the form of evaporator adapted to be usedasa'p'art of the system of Fig. l. v

In the drawings, and referring first to Fig. l, numeral l0 designates acasing which preferably is of cylindrical form having legs ll adapted torest upon any appropriate foundation-sonnet the casing may serve as theeffective ba e of the machine. One end portion of this casing (Fig; 2)houses a bank of tubes I2 which, asmay be seen, are provided witha'large number of surface extending fins l3, and are interconnected witha water-box I4. This end portion of casing it accordingly serves as theshell ofthe evaporator of the system in which refrigerant liquidmay bevaporized to abstract heat from water or any other desired mediumcirculated through the tube bank. p

The first compressor unit l5, comprising com pressor stages A and 13,their common driving In the preferred construction, a second casing l8,again of cylindrical form, is mounted atop 55.

second casing having legs l9 welded or otherwise secured to itsunderside and resting upon similar legs 20 aflixed to the upper part ofcasing Ill. The second compressor unit 2| of the system, 0 includingcompressor'stages C and D, their commotor [6 and accessories, is housedin the other the combination evaporator-compressor unit, the

mon driving motor 22 and accessories, is housed in one end of casing 18immediately above the first compressor unit l5 in casing lflfand the endof casing i8 is. covered by a manifold 23. When the system is operating,the partially compressed refrigerant vapor discharged from stage B ofthe first compressor unit passes through manifold M, fitting 24, andmanifold 23 into stage C, is further compressed therein, and is thendischarged over and through the motor 22 to cool that element. The laststage, D, withdraws partially compressed vapor from that part of casingI! which serves as a housing for the second compressor unit, raises thepressure of the vapor to a desired final value, and discharges it intothe remaining portion of easing [8.

The last-mentioned casing portion is adapted to serve as the shell ofthe condenser of the system, and in it is housed a bank of tubes 21which carry a large number of surface extending fins 23 and have theirends interconnected with the water-box 29. Accordingly, the compressedvapor discharged from stage D passes over the bank of tubes, gives upits heat to water circulating through the bank, and is condensed, theresulting refrigerant collecting in the base of the shell (casing l8),whence it may be returned to the evaporator through conduit 3! forre-use.

The refrigerating machine which has been generally described above isprimarily designed to operate with one of the so-called low-pressurerefrigerants, such as trichloro-trifiuoro-ethane or the like. Thesesubstances, as is well recognized in the art, are almost ideally suitedto centrifugal compression. Accordingly, each of the compressor units l5and M includes two stages of centrifugal compression each comprising animpeller adapted to be driven directly by the motor of the unit, and adiffuser surrounding the impeller,

the latter element serving in the well-understood manner to convert thevelocity pressure of vapor issuing from the impeller into a static head.These two units are so nearly identical in basic design that aconsideration of one of them will sumce to bring out the features ofboth and the manner in which they are mounted in their respectivecasings. For this purpose the first compressor unit I5 and its mountingin the evaporator casing Ill will be described in detail.

In assembling the unit I5, and starting with stage A, the inner half 32of the diffuser (generally designated 33) is slipped over the shaft 34of motor l5, and its flange 35 is bolted at 35 to a flange 31 of themotor casing. It will be seen that the flange 35 is formed at the rearend of a spider 38 which comprises an integral part of the diffuser,element 32, and that this spider has a series of openings 33 throughwhich some vapor may pass from the outlet 40 of the diffuser through andover the windings of the motor I to cool those parts. If it has notalready been set in place, the gland 42 (Fig. 3) is slipped over theshaft 34 and is bolted at 43 to the difluser element 32 to provide alabyrinth packing around the shaft at this point.

The impeller 44 is next fitted and keyed to the shaft,'and a spanner nut45 is applied to the end of the shaft to hold the impeller in place. Itwill be noted (Fig. 3) that this nut has smoothly rounded surfaces whichcomplement those of the impeller, whereby friction between therefrigerant vapor and the impeller may be minimized. After the impellerhas been mounted, the outer half 45 of the diffuser 33 can be fitted inplace, and bolted to the inner half 32 at 41.

Finally, the inlet guard 48 is bolted or otherwise secured to thediffuser element 45. It will be noted at this point (Fig. 3) that thesurface of the inlet guard is smoothly rounded, and is so designed as tocomplement the adjacentsurfaces of the inlet of the impeller-all to theend that friction between the refrigerant vapor and the parts of themachine may be kept as low as possible. While the inlet guard must nottouch the impeller, the clearance between these parts is small, and theguard is provided with a series of labyrinths 49 which effectivelyprevent the shorteircuiting of any substantial volume of vapor from thedischarge of the impeller 44 around the inlet guard to its inlet.

The assembly of stage 13 of the unit is quite,

similar to that of stage A. Specifically, and referring to Fig. 1, theinlet guard 5| is first applied to the inner half 52 of the diffuser(generally designated 53), that inner half is slipped over the motorshaft 34, and its flange 54 is bolted at 55 to the flange 56 of themotor casing. Here, again, it will be noted that the flange 54 is spacedfrom the main body of the diffuser by a spider, the spaces between thearms 51 of the spider again allowing for the flow of vapor through themotor windings and into the second stage impeller. The impeller 58 isthen fitted and keyed to the shaft 34, and a nut 59 is applied to securethe impeller in place. When this has been done, some adjustment of theinlet guard 5| may be needed to insure that the guard and the impellerdo not touch. Here, again, the outer surface of the guard is smoothlyrounded to complement the surface of the impeller inlet; and the guardis provided with labyrinths to restrict the flow of vapor between thatguard and the adjacent surface of the impeller. The assembly of thecompressor unit I5 is completed by the application of the outer half 60of the diffuser, this element being bolted at 5| to the inner half 52(Fig. 1).

It is evident that the first compressor stage A must handle a largervolume of refrigerant vapor than the second stage B, the volumetricdifference being accounted for by the fact that the vapor is partiallycompressed in the first stage before it is delivered to the secondstage. Accordingly, and as is shown in Fig. 1, the diffuser 33 and theimpeller 44 of stage A are somewhat larger than the like parts of stageB.

It will be noted that the two impellers are mounted directly upon themotor shaft and are supported by the bearings for that shaft (notshown). Each of these bearings is provided with an independentlubricating system 52, which may be constructed in accordance with thedisclosure of copending application Serial No. 232,580, filed September30, 1938 (now patent No. 2,266,107, dated December 16, 1941). Referencemay be had to that application for more complete details of thelubricating system and its manner of operation. The prime differencebetween the system there disclosed and the one here shown lies in thefact that the oil-settling chambers 53 are mounted directly upon theframe of the motor l6, rather than upon the casing of the unit.

The assembled compressor unit i5 is of such size and shape that it mayreadily. be passed through the open end of easing Ill, and he slippedalong rails 54 which serve both to guide and to support it until themarginal flange 55 of the diffuser element 32 of, stage A (Fig. 3)forces a packing ring 55 into engagement with an annular flange 61formed on the inside of casing H). The

. to": form a leaktight joint between the compressor Qunit 'and thatpart of casing III which serves as hell of the evaporator of the system.Finally, the? manifold I! may be bolted in place, as indicated at 1I, tocover the end of the casing.

The manhole I2 (Fig. 2) gives access to the inside of the casing IIIafter the compressor unit has been inserted for making the necessaryelectric'alconnections of the motor I6, and for connecting pipes 13 and"leading from the settling chambers 63 of the oiling systems to thebull's- :eyes 15which are mounted on casing I0. These 'b ills-eyes givea visual indication of the quantity of oil in the lubricating systems.This oil may be supplied in the, first instance, or more may be added,through filling cups I6 which are connected with the bulls-eyes throughpipes 11, and, accordingly, with the lubricating systems through theabove-mentioned pipes 14. Whenall of the internalconnections have beenmade, the cover 18 may be applied to the casing over the manhole 12 toseal the unit at this point.

The basic design of the second compressor unitZI is quite similar tothat of the first unit l5, as has already been pointed out. Thesedifferences, however, should be noted. 'Stage ,0 of the second unit isassembled in substantially the same manner as stage A of the first unit;and the assembly of stage D follows that of stage B. Here, again, itwill be evident thatthe stages are of progressively decreasingvolumetric capacity, the impeller I9 andthe diffuser 30 of the thirdstage C being of somewhat lesser diameter than the comparable parts ofthe second stage B, and the.

impeller ill and the diffuser 82 of the fourth stage D being of lesserdiameter than the comparable parts of the third stage C. c Thecompletely assembled unit 2| may be insorted through the open end ofeasing I3, and the procedure is much like that followed in mounting thefirst compressor. unit IS in the evaporator casing I0. The diifuser 890istage C has a flange 83, which is comparible in function to the flange930i stage B, whereby it may be bolted to an end flange 84' of thecasing l8, and the diffuser B2 of stage D has a right-angle flange 85 atits edge which is'cornparableIto the flange 65 of diffuser element 32 ofstage A. Accordingly, the bolts 86 serve to drive the entire unit intothe casing, and to cause flange 86 to compress a gasket 81 against anannular internal flange 88 formedlon the casing I8 to form a leak-tightjoint at that point. The manifold 23 may then be,

b01ted;-:'at 90 to the end of casing I8.

When the foregoing steps have been completed, 60 I the electricalconnections may be made to the nor the manhole and its cover are shownin the drawings, but these parts-may be identical with the comparableones shownv in Fig. 2, and furtherillustration and description areunnecessary.

The various constructional differences between the two compressor unitsand their individual stages are well illustrated in the drawings andneed not be further described.

45 which lies inside of bend I00.

which the manifolds I1 and 23 are bolted in' place. The manifolds maythen be connected by the fitting 24, which preferably comprises asection of copper or brass tubing having flanges at its ends forconnection to the flanges of the caps l1 and 23, and a peripheral foldat some point between its ends. The fitting is thus adapted to serve asan expansion point between the two compressor units, the fold collapsingor extending to take up an expansion or contraction of the variousparts.

The details of the evaporator are well illustrated in Figs. 2, 4 and 5.In that structure the tube bank I2 includes a bundle of tubes 93 havingplate fins I3 applied at closely spaced intergo vals to increase theirheat-transfer surfaces. It

is evident, however, that spiral-finned tubing, or any form of extendedheat-transfer surface, may

be used in building up the bank.

The individual tubes 93 are interconnected by 25 return bends at one endof the bank I2 whereby -all supply and discharge connections may be madefrom the other end of the bank. These bends may be applied to the tubesin such a way as to define two or several liquidpasses, according to theneeds of the case.

" 96. -The fifth and eighth tubes of this row are connected by returnbend 98; and the sixth, and seventh tubes by band 99. A specificdescription of the interconnection of the remaining tubes of the firstrow is unnecessary since. it is readily evident from Fig. 5.

, The tubes of the second row lie between those of the first (see Fig.4) In this row, return bend IIlIljolns the firstzand fourth tubes; andthe sec- 0nd and third tubes are connected by bend IIII, The fifth andsixth tubes are connected by bend I02; and the remaining tubes of thesecond row are similarly a joined together. The application of returnbends to the third, fifth, seventh, etc., rows follows that of the firstrow; and the tubes of the fourth,

sixthf**eighth, etc., rows are interconnected precisely-as are those ofthe second. It is of course evident that other forms of interconnectionof the tubes may be employed if desired.

It will be noted (Figs. 4 and 5) that the tubes 93 are so arranged as todivide the bank I2 into two distinct sections, and to leave apassageway- IM extending vertically and longitudinally through itscenter. In the illustrated embodiment the two sections are spaced apartby the channels I05, and by a pair of plates I03 which are disposedalong the edges of the fins adjacent the bottom of the bank. It isthrough the peasageway I04 that liquid refrigerant is introduced 55 intothe bank and is distributed over its surfaces in a manner later to beconsidered.

- Zilrof the tubes, their fins, the channels, plates,

etc., are bound together by the end plates I01, the intermediatesupporting plates I08, and the tube sheet I09 (Figs. 2 and 5). The bankI2 may,

accordingly, be slipped as a unit through the opening in the end wallIII of easing Ill along rails II2 which serve both to guide the bank andto support it; and the bank is secured in place It is the usual practicein assembling a refrigby the bolting-on of' the water-box I4.

The other constructional details of the evaporator may best beunderstcod from a consideration of the operation of that device. Thus.and referring to Figs. 2 and 4, liquid refrigerant returning from thecondenser of the system through line 3I passes into a conduit II3 which,in the illustrated structure, is welded to the underside of the casingI0, and, through a series of orifices I I4, into the base of the casing.These orifices are located immediately beneath the passageway I04through the tube bank I2. The introduced liquid is thus directed throughthe pool of refrigerant already in the base of the shell and into thepassageway I04. Its flash gas generates a froth of the liquid in thepool, which, being lighter than the liquid, rises into the passageway.There the vapor is confined by the channels I05 and the plates I08 sothat it be-- comes most effective in lifting the liquid.

When the froth passes over the edges of the plates I06,'it begins tospread sidewise. Immediately some of its liquid component is evaporatedby heat transfer with the water flowing through tubes 93. At this pointit will be noted that the plates 95 are arranged along the outer sidesof the bottom portion of the bank. These plates serve primarily toconfine the vapor generated in the lower portion of the bank, and toprevent its immediate escape through the sides of the bank. Some of thevapor finds a path for escape by flowing back toward the centralpassageway I04, where it augments the vapor already present and assistsin lifting the froth through the passageway; the ramainder flows upthrough the bank and assists in the circulation of liquid therethrough.

A portion of the liquid and vapor, which rises all of the way tothe topof the passageway I04, blows against baffle H5 and is directed .by thatelement to the sides of the tube bank, so that its liquid content mayflow downwardly over the outer tubes to keep them thoroughly wetted.

Excess liquid drains from the tubes and their flns into the pool in thebase of the casing, whence it may be recirculated through the bank inthe manner just described. In this connection it will be noted that thevertical parts of the plates 95 extend almost, but not quite, to thesurface of the casing I0, so that excess liquid may fiow under theiredges whenever necessary.

Refrigerant vapor passes off through the top and the upper sides of thebank, and flows through an eliminator IIB (Fig. 2) which is supend ofthe evaporator proper, and a second crossplate IIO which depends fromthe top of the easing. This eliminator is of more or less usualconstruction and, of course, serves the conventional function ofseparating vapor from any entrained droplets of liquid, allowing theformer to pass to the inlet of impellent 44 of stage A of the firstcompressor unit, and the droplets of liquid to fall back into the baseof the shell on the evaporator side of the partition II.

The system may be charged with refrigerant through valve I34 and. pipeI35 (Fig. 2). In order that these elements may also be used for drainingthe system, whenever that becomes necessary, the pipe has its lower enddisposed in a sump I30 which is formed on conduit ,,I I3, ,the lowestpoint in the system.

A modified form of evaporator, constructed and designed to operate inaccordance with the principles of the invention, is illustrated in Fig.

ported between a cross-plate II'I, defining the two vertical passagewaysI22 extending for its full length and height, and beneath each of themis a series of orifices I23 formed in the deckplate I24 which definesthe effective base of the shell I25. In operation, liquid refrigerantreturning from the condenser through conduits I28 is directed upwardlyfrom these orifices through the pool of refrigerant collecting on thedeck-plate, and into the passageways I22.

Here,'again, the incoming refrigerant provides an initial volume offlash gas to generate a froth of the liquid in the pool, and to startcirculation of liquid and vapor through the passageways I22. Some of theliquid and vapor will rise all of the way to the top of the bank andstrike against the baflles I2I which break up the froth and throw theliquid to the sides of the bank where it may flow downwardly over thetubes I28 and fins I29, while other portions of the froth spreadsidewise over the edges of the confining plates I30 and through thebank; Any vapor generated in the lower portions of the bank is confinedby side plates I3 I. Since it cannot immediately escape through thesides of the bank, it must pass upwardly to assist in the circulationprocess.

The construction of the condenser tube bank 21 need not be considered ingreat detail. Sufllce it to say that the various tubes are assembledwith their plate fins 23 (other forms of the extended surface may, ofcourse, be employed, if desired), and the individual tubes areinterconnected at one end of the bank by return bends I3I so that alloutside supply and discharge connections may be made from the other endof the I bank; and. the tubes, fins, etc. are bound together byappropriate end plates I38, intervening supporting sheets (not shown)and by the tube sheet I32. The entire bank is of such size and shapethat it may be slipped as a unit through the end of easing I8 alongrails I33 which serve both to guide and support it; and the bank may besecured in place to the casing I8 by the bolting-on of the water-box 29.

Since certain changes may be made in the construction of therefrigerating unit as a whole, the arrangement of its constituent parts,and in its operation, the foregoing is intended to be construed in adescriptive rather than in a limiting sense.

What I claim is:

l. A shell-and-tube refrigerant evaporator of the type wherein the tubebank is not submerged in liquid refrigerant, such evaporator compris-.

ing a shell adapted to serve as a part of a closed path for arefrigerating fluid, a bank of tubes adapted to serve as apath for afluid to be cooled, some of said tubes being spaced apart to leave asubstantially clear passageway extending vertically and longitudinallythrough the bank, and means for introducing liquid refrigerant into thebase of said shell, said means being adapted to distribute theintroduced refrigerant lengthwise of said bank and to direct liquidrefrigerant and flash gas upwardly into the passageway of the bank, saidpassageway being of such proportions as to confine tneflash gaslaterally whereby to cause it to lift liquid refrigerant through saidpassageway and to distribute it over said tubes.

2. A shell-and-tube evaporator according to I claim 1, furthercharacterized by the provision of means for confining laterally vaporwhich is 6. In this arrangement the tube bank I2I has 7 generated in the10We1 Part of the bank whereby to cause that vapor to rise through thebank and through said passageway.

33. A shell-and-tube evaporator according to claiml, furthercharacterized by the provision of fins on said tubes, and platesextending along the sides of the tube bank, said plates serving toconfine any vapor which is generated in the lower part of the bankwhereby to constrain that vapor to fiow upwardly through said bank andthrough said passageway.

4. A shell-and-tube evaporator according to claim 1, furthercharacterized by the provision of a pair of plates arranged along thesides of said passageway near the bottom of said bank, said platesserving to confine laterally flash gas which is directed into thepassageway whereby such gas may serve to lift liquid through thepassageway; and by the provision of other plates extending along thesides of the tube bank, said other plates serving to confine laterallyvapor which is generated in the lower part of the bank whereby toconstrain it to pass upwardly through said bank and said passageway.

5. A shell-and-tube evaporatorv according to claim 1, furthercharacterized by the provision of fins on said tubes, and platesextending along the sides of the tube bank from its bottom to a pointbelow its top, said plates serving to confine any vapor generated in thelower part of the bank whereby to constrain that vapor to fiow upwardlythrough said bank and through said passageway, and a baille arrangedabove said tube bank and over the upper end of said passageway therein,said baifie serving to break up any froth of liquid refrigerant andvapor issuing from the upper end of said passageway and to direct theliquid portion thereof outwardly to the sides of the bank so I that itmay fiow downwardly over said tubes.

6. A shell-and-tube refrigerant evaporator comprising a shell, a bank oftubes having fins applied to their outer surfaces disposed in saidshell, said tubes being so arranged as to leave a substantially clearpassageway extending lengthwise and vertically through the bank andhaving its lower open end located adjacent to but spaced from the baseof the shell, a conduit having a series of orifices therein fordischarging liquid refrigerant into the base of the shell through thesmall pool of liquid refrigerant which accumulates therein and fordirecting the introduced liquid and its flash gas into the lower openend of said passageway, such passageway serving to confine the fiash gaslaterally whereby it may serve to lift liquid refrigerant through saidpassageway for distribution over the tubes and their fins.

'7. A shell-and-tube refrigerant evaporator according to claim 6,further characterized in that the said orifices are formed in the baseof said shell, and in that said shell comprises a part of said conduit,

8. A shell-and-tube refrigerant evaporator according to claim 6, furthercharacterized by the provision of a bafile disposed above the upper endof said passageway, said bame being of generally- V-shaped cross sectionwith its legs curved outwardly whereby it may serve to break up anyfroth of refrigerant liquid and vapor striking against its undersurfaces and to direct the liquid to the sides of the bank so that itmay flow downwardly over said tubes and their fins.

9. A shell-and-tube refrigerant evaporator according to claim 15,further characterized by the provision of means at the sides of saidtube bank for confining refrigerant vapor generated in the lower portionof the bank whereby to constrain it to fiow upwardly through said bankand said passageway.

10. A shell-and-tube refrigerant evaporator, according to claim 6,further characterized by the provision of a pair of substantiallyparallel plates disposed at the sides of said passageway and extendingfrom a point near the bottom of the bank upwardly past the first fewrows of tubes of the bank; and additional plates at the outer sides ofthe bank serving to confine laterally vapor which is generated in thelower portion of the bank whereby to constrain it to fiow upwardlythrough said bank and through said passageway.

11. A shell-and-tube refrigerant evaporator according to claim 6,further characterized by the provision of means along the lower sideportions of the bank serving to confine laterally vapor which isgenerated in the lower part of the bank whereby to constrain it to fiowup throughthe bank and said passageway; and by the provision of a bafliedisposed above said bank of tubes and over the upper end of saidpassageway, said baffle being of generally V-shaped cross sectionwhereby it may serve to break up any froth of refrigerant liquid andvapor issuing from the upper end of said passageway and to direct theliquid to the outer sides of the bank whence it may fiow over the tubesand return to the base of the shell.

12. A shell-and-tube evaporator according to claim 6, furthercharacterized in that said tubes i are so arranged as to leave aplurality of such passageways through the bank, and in that there is aconduit having a series of distributing orifices therein disposedbeneath each of such passageways to direct refrigerant liquid and vaporthereinto.

13. A shell-and-tube refrigerant evaporator comprising a shell, 9. bankof tubes having fins applied to their outer surfaces disposed in saidshell, said tubes being arranged to leave two substantially clearpassageways extending lengthwise and vertically through the bank andhaving their lower open ends located adjacent the base of said shell, aconduit having a series of distributing orifices therein disposedbeneath each such passageway, said orifices serving to introduce liquidrefrigerant into the base of the shell through the small pool of liquidaccumulating therein and to direct refrigerant liquid and vapor into thelower ends of said passageways, said passageways being of such size asto confine such refrigerant vapor laterally, thus causing the vapor togenerate a. froth with the liquid, which froth will rise through thepassageways, a baiile disposed above the upper open end of each of saidpassageways, said baiiles serving to break up any froth of refrigerantliquid and vapor issuing from the upper ends of said passageways and todirect the liquid sidewise so that it may flow downwardly over the tubesand their fins, and means at the sides of such tub bank for confiningvapor generated in the lower portions of the bank whereby to constrainit to flow upwardly through said bank.

ROBERT w. WATERFILL.

CERTIFICATE OF CORRECTION. Patent No. 2,l{.1,152. Februery 19%.

ROBERT w. WATERFILL.

It. is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 5,secondcolumn, line 2, for the claim reference numeral "15" read "--6"-;and

that-the said Letters Patent should be read with this correction thereinthat the same may conform to the record of the case in the PatentOffice.

si ned and sealed this 11th day of April, A. 1;. 191m.

Leslie Frazer .(Seal) Acting Commissioner of Patents.

